Big screen displays are widely used in business and daily life.
Chinese Patent CN1217539C, for example, described a tapered waveguide display with a conventional projector, whose advantages include omission of light path required for conventional projection, thinner than traditional back projection display, so that it is comparable with liquid crystal or plasma displays. Since waveguide displays can be made of inexpensive optical glass or transparent plastics, costs for making large screens will be much lower than traditional flat panel techniques such as liquid crystal or plasma displays. In addition, waveguides do not contain any electronic components, therefore they are stable and robust compared with liquid crystal, plasma or LED displays. However, due to complex structures of the back side, serious distortions are introduced, which result in difficulty in designing such projection systems and the complicated geometric construction is also a disadvantage for mass production.